Puma Announces Availability of NERLYNX™ (neratinib) for Extended
Adjuvant Treatment of HER2-Positive Early Stage Breast Cancer in the
United States

NERLYNX is the first anti-HER2 treatment to be FDA-approved as
extended adjuvant therapy for early stage HER2-positive breast cancer
following adjuvant trastuzumab-based therapy.

Treatment with NERLYNX resulted in a 34% reduction in the risk of
invasive disease recurrence or death versus placebo after patients
completed one year of therapy following a trastuzumab-based regimen.

NERLYNX addresses an unmet medical need, as up to 25% of
HER2-positive early stage breast cancer patients treated with
trastuzumab-based adjuvant treatment experience a recurrence.

July 31, 2017 04:20 PM Eastern Time

LOS ANGELES--(EON: Enhanced Online News)--Puma Biotechnology, Inc. (Nasdaq: PBYI) announced thatNERLYNX™
(neratinib) tablets, formerly known as PB272,is now commercially
available by prescription in the United States. The U.S. Food and Drug
Administration (FDA) approved NERLYNX on July 17, 2017 for the extended
adjuvant treatment of adult patients with early stage
HER2-overexpressed/amplified breast cancer, following adjuvant
trastuzumab-based therapy.

“We are pleased
to be able to bring this new medicine to patients with breast cancer. We
would like to express our appreciation to the patients, caregivers and
physicians who contributed to the NERLYNX clinical development program
and, more specifically, the ExteNET trial.”

FDA approval was based on the Phase III ExteNET trial, a multicenter,
randomized, double-blind, placebo-controlled trial of NERLYNX following
adjuvant trastuzumab treatment. Women (n=2,840) with early stage
HER2-positive breast cancer and within two years of completing adjuvant
trastuzumab were randomized to receive either NERLYNX (n=1,420) or
placebo (n=1,420) for one year.

The results of the ExteNET trial demonstrated that after two years of
follow-up, invasive disease-free survival (iDFS) was 94.2% in patients
treated with NERLYNX compared with 91.9% in those receiving placebo (HR
0.66; 95% CI: 0.49, 0.90, p=0.008).

The most common adverse reactions (≥5%) were diarrhea, nausea, abdominal
pain, fatigue, vomiting, rash, stomatitis, decreased appetite, muscle
spasms, dyspepsia, AST or ALT increase, nail disorder, dry skin,
abdominal distention, epistaxis, weight loss, and urinary tract
infection. The most common adverse reaction leading to discontinuation
was diarrhea, which was observed in 16.8% of NERLYNX-treated patients.
Increases in liver transaminases led to drug discontinuation in 1.7% of
NERLYNX-treated patients.

“Like many women with breast cancer, those with HER2-positive disease
often struggle with anxiety and fear of recurrence,” said Jennifer
Merschdorf, Chief Executive Officer of Young Survival Coalition. "We are
always eager for treatment advances that may provide an opportunity to
further reduce the risk of recurrence.”

“Despite advances in the treatment of early stage HER2-positive breast
cancer, there remains a need for further therapeutic improvements in
order to attempt to further reduce the risk of disease recurrence,” said
Puma Biotechnology CEO and President Alan H. Auerbach. “We are pleased
to be able to bring this new medicine to patients with breast cancer. We
would like to express our appreciation to the patients, caregivers and
physicians who contributed to the NERLYNX clinical development program
and, more specifically, the ExteNET trial.”

To help ensure patients have access to NERLYNX, Puma has implemented the
Puma Patient Lynx support program to assist patients and healthcare
providers with reimbursement support and referrals to resources that can
help with financial assistance. More information on the Puma Patient
Lynx program can be found at www.NERLYNX.com
or 1-855-816-5421.

The full prescribing information for NERLYNX is available at www.NERLYNX.com.
The recommended dose of NERLYNX is 240 mg (six 40 mg tablets) given
orally once daily with food, continuously for one year. Antidiarrheal
prophylaxis should be initiated with the first dose of NERLYNX and
continued during the first 2 months (56 days) of treatment and as needed
thereafter.

A Marketing Authorisation Application for neratinib is under review by
the European Medicines Agency (EMA).

About HER2-Positive Breast Cancer

Approximately 20% to 25% of breast cancer tumors over-express the HER2
protein. HER2-positive breast cancer is often more aggressive than other
types of breast cancer, increasing the risk of disease progression and
death. Although research has shown that trastuzumab can reduce the risk
of early stage HER2-positive breast cancer returning after surgery, up
to 25% of patients treated with trastuzumab experience recurrence.

Indication

NERLYNX™ is a tyrosine kinase inhibitor indicated for the extended
adjuvant treatment of adult patients with early stage
HER2-overexpressed/amplified breast cancer, to follow adjuvant
trastuzumab-based therapy.

Important Safety Information

There are possible side effects of NERLYNX. Patients must contact their
doctor right away if they experience any of these symptoms. NERLYNX
treatment may be stopped or the dose may be lowered if the patient
experiences any of these side effects.

Diarrhea

Diarrheais a common side effect ofNERLYNX. The diarrhea
may be severe, and you may get dehydrated. Your healthcare provider
should prescribe the medicine loperamide for you during your first 2
cycles (56 days) of NERLYNX and then as needed. To help prevent or
reduce diarrhea:

You should start taking loperamide with your first dose of NERLYNX.

Keep taking loperamide during the first 2 cycles (56 days) of NERLYNX
treatment and then as needed. Your healthcare provider will tell you
exactly how much and how often to take loperamide.

While taking loperamide, you and your healthcare provider should try
to keep the number of bowel movements that you have at 1 or 2 bowel
movements each day.

Tell your healthcare provider if you have more than 2 bowel movements
in 1 day, or if you have diarrhea that does not go away.

Contact your healthcare provider right away if you have severe
diarrhea or if you have diarrhea along with weakness, dizziness, or
fever.

Liver Problems

Changes in liver function tests are common with NERLYNX. The patient’s
doctor will do tests before starting treatment, monthly during the first
3 months, and then every 3 months as needed during treatment with
NERLYNX. NERLYNX treatment may be stopped or the dose may be lowered if
your liver tests show severe problems. Symptoms of liver problems may
include tiredness, nausea, vomiting, pain in the right upper stomach
area (abdomen), fever, rash, itching, yellowing of your skin or whites
of your eyes.

Pregnancy

Patients should tell their doctor if they are planning to become
pregnant, are pregnant, plan to breastfeed, or are breastfeeding.
NERLYNX can harm your unborn baby. Birth control should be used while a
patient is receiving NERLYNX and for at least 1 month after the last
dose. If patients are exposed to NERLYNX during pregnancy, they must
contact their healthcare provider right away.

Patients should tell their doctor right away if they are experiencing
any side effects. Report side effects to the FDA at 1-800-FDA-1088 or http://www.FDA.gov/medwatch.
Patients and caregivers may also report side effects to Puma
Biotechnology at 1-844-NERLYNX (1-844-637-5969).

Puma Biotechnology, Inc. is a biopharmaceutical company with a focus on
the development and commercialization of innovative products to enhance
cancer care. The Company in-licenses the global development and
commercialization rights to three drug candidates—PB272 (neratinib
(oral)), PB272 (neratinib (intravenous)) and PB357. NERLYNX is a potent
irreversible tyrosine kinase inhibitor that blocks signal transduction
through the epidermal growth factor receptors, HER1, HER2 and HER4.
Currently, the Company is primarily focused on the development of the
oral version of NERLYNX , and its most advanced drug candidates are
directed at the treatment of HER2-positive breast cancer. The Company
believes that NERLYNX has clinical application in the treatment of
several other cancers as well, including non-small cell lung cancer and
other tumor types that over-express or have a mutation in HER2. Further
information about Puma Biotechnology can be found at www.pumabiotechnology.com.

Forward-Looking Statements

This press release contains forward-looking statements, including
statements regarding the potential benefits ofNERLYNX. All
forward-looking statements included in this press release involve risks
and uncertainties that could cause the Company's actual results to
differ materially from the anticipated results and expectations
expressed in these forward-looking statements. These statements are
based on current expectations, forecasts and assumptions, and actual
outcomes and results could differ materially from these statements due
to a number of factors, which include, but are not limited to, the fact
that the Company currently has no product revenue, the Company's
dependence upon the commercial success of NERLYNX™ (neratinib), the
Company’s history of operating losses and its expectation that it will
continue to incur losses for the foreseeable future, risks and
uncertainties related to the Company’s ability to achieve or sustain
profitability, the Company’s ability to predict its future prospects and
forecast its financial performance and growth, failure to obtain
sufficient capital to fund the Company’s operations, the effectiveness
of sales and marketing efforts, the Company’s ability to obtain FDA
approval or other regulatory approvals for others product candidates,
the challenges associated with conducting and enrolling clinical trials,
the risk that the results of clinical trials may not support the
Company's drug candidate claims, even if approved, the risk that
physicians and patients may not accept or use the Company's products,
the Company's reliance on third parties to conduct its clinical trials
and to formulate and manufacture its drug candidates, risks pertaining
to securities class action, derivative and defamation lawsuits, the
Company's dependence on licensed intellectual property, and the other
risk factors disclosed in the periodic and current reports filed by the
Company with the Securities and Exchange Commission from time to time,
including the Company's Annual Report on Form 10-K for the year ended
December 31, 2016. Readers are cautioned not to place undue reliance on
these forward-looking statements, which speak only as of the date
hereof. The Company assumes no obligation to update these
forward-looking statements, except as required by law.